Time to go stage II with A/C!

[Alky V6]

Unless your going to a smaller set of injectors (probably a good idea), try to stay above the minimum suggested IPW for your injectors. If you're still too rich after all that, install smaller injectors.

 

[Alky V6]

Make sure the MAP signal to the ECM is correct. Check it against a manual vacuum gauge.

 

[Alky V6]

It's been awhile since I've played with a XFI system. How are you adjusting the ipw once you get it started and at a steady rpm? Assuming the O2 correction is off. Through the VE table? Or, a base fueling curve?

 

[Mike E]

Maybe you've already adjusted it, but do you have a lot of coolant temp correction at low temps? I see 45* cts on your log. You went to a bigger injector, maybe you don't need as much correction %.

 

[kidglok]

Have you verified the voltage that the xfi is seeing is actually what's at the injectors? I've seen it off almost a full volt

 

[Alky V6]

Maybe you've already adjusted it, but do you have a lot of coolant temp correction at low temps? I see 45* cts on your log. You went to a bigger injector, maybe you don't need as much correction %.

If coolant temp correction was being added to the ipw, it still left the ipw lower than the manufacturers recommended minimum ipw.
IIRC, Norbs backed out all the corrections to fueling.

 

[norbs]

Unless your going to a smaller set of injectors (probably a good idea), try to stay above the minimum suggested IPW for your injectors. If you're still too rich after all that, install smaller injectors.

This is why I bought 120's so I could idle nice and mean and lean, but I guess I was wrong. 95's will not support the HP levels I am targeting, but you could be right they are too big

 

[norbs]

Made some progress lowered the voltage to 16 volts set the opening time to .6 as per Dusty's suggestion and it ran a bit better, af in the mid 10s to 11's, and I put hotter plugs in, but I think I just fouled another one...it started to miss again, after I restarted it.

 

[Alky V6]

Made some progress lowered the voltage to 16 volts set the opening time to .6 and it ran a bit better, af in the mid 10s to 11's, and I put hotter plugs in, but I think I just fouled another one...it started to miss again.

I was going to mention something about that. I saw that high voltage in the datalog. That would make the injectors react faster which would require a smaller pw to deliver the same amount of fuel as an injector operating at a lower voltage. Maybe you need to keep lowering the voltage and maybe getting to a point of having to increase the pw until you can get that pw at idle above the suggested minimum.

 

[Alky V6]

Not sure why you need that much voltage at idle, but can you have the voltage closer to 13.5 V at idle, and then ramp up or step up to the higher value at a particular boost level?

Your voltage compensation table is going to have to be right on to avoid a change in fueling when the higher voltage kicks in.

 

[norbs]

Not sure why you need that much voltage at idle, but can you have the voltage closer to 13.5 V at idle, and then ramp up or step up to the higher value at a particular boost level?

Your voltage compensation table is going to have to be right on to avoid a change in fueling when the higher voltage kicks in.

The idea was to reduce opening time so it runs leaner, but it does not seem its working that way, sure I can lower it and see what happens.

If you look at the log you can see the af in green and when it goes leaner it starts to spike more, same with idle rpm.

 

[Alky V6]

A higher voltage is nice for the starter and for the fuel pump if you're trying to extend the delivery volume of the pump, but the injectors, unless they're designed to be run at 16 volts, should be run at a steady voltage that they're designed to be run at.

 

[Alky V6]

That's pretty much expected. As you bring the a/f ratio more inline with what the engine likes, the rpm will come up and vacuum should increase.

 

[norbs]

A higher voltage is nice for the starter and for the fuel pump if you're trying to extend the delivery volume of the pump, but the injectors, unless they're designed to be run at 16 volts should be run at a steady voltage that they're designed to be run at.

Supposedly they can be run up to 20 volts!

 

[Alky V6]

Supposedly they can be run up to 20 volts!

But, if you can't get the pw small enough for your particular application at a higher voltage, what's the use?

 

[Alky V6]

The perfect situation would be to run the injectors at a low voltage at idle so that your idle pw is not having to run at the minimum, and have the voltage RAMP in under boost. That is if you need to extend the delivery volume of the injectors to feed the engine under high horsepower demand.
If the injectors will handle the fuel volume at max power demand being operated at 13.5 volts, then running at a higher voltage is a waste and just runs the injectors hotter than necessary.

 

[norbs]

The perfect situation would be to run the injectors at a low voltage at idle so that your idle pw is not having to run at the minimum, and have the voltage RAMP in under boost. That is if you need to extend the delivery volume of the injectors to feed the engine under high horsepower demand.
If the injectors will handle the fuel volume at max power demand being operated at 13.5 volts, then running at a higher voltage is a waste and just runs the injectors hotter than necessary.

I think your on to something here, as I increased the voltage the car would get richer.........is this supposed to happen?

 

[Alky V6]

I think your on to something here, as I increased the voltage the car would get richer.........is this supposed to happen?

For a given pw on a given injector, as the operating voltage is increased the injector will react quicker and because of that deliver more fuel. That is what the voltage compensation table is for. But, if you can't lower the pw enough at the higher voltage to meet your fuel delivery target, then the voltage must be decreased.

If the voltage compensation table is set up correctly, the fuel delivery volume should not change with changing voltages.

 

[norbs]

Have you verified the voltage that the xfi is seeing is actually what's at the injectors? I've seen it off almost a full volt

Seems like I'm losing .5 volts between the inj and XFI..

 

[Dusty Bradford]

Continue to lower the injector offset to get the ve and af numbers your looking for. Try .4 instead of .6 and it should get even leaner.